The present invention is directed to ink compositions. More specifically, the present invention is directed to waterfast ink compositions particularly suited for ink jet printing processes. One embodiment of the present invention is directed to an ink composition which comprises water, a water-soluble dye, a first component selected from the group consisting of sulfones and mixtures thereof, and a second component selected from the group consisting of cyclic amines having at least one hydrogen atom bonded to a nitrogen atom, cyclic amides having at least one hydrogen atom bonded to a nitrogen atom, diamides having at least one hydrogen atom bonded to a nitrogen atom, polyalkoxy-substituted or polyimine-substituted amides having at least one hydrogen atom bonded to a nitrogen atom, and mixtures thereof.
Ink compositions for ink jet printing are known. For example, U.S. Pat. No. 5,017,227 (Koike et al.) discloses a recording liquid comprising dyes and a liquid medium, wherein the dyes include a black dye and at least one water-soluble dye of a magenta dye and a yellow dye in combination. The black dye is selected from the group C.I. Food Black 1, C.I. Acid Black 140, and C.I. Acid Black 187. The liquid medium is water-based, and can contain a water-soluble organic solvent. Examples of water-soluble organic solvents include alkyl alcohols having 1 to 5 carbon atoms, amides such as dimethylformamide and dimethylacetamide, ketones or ketoalcohols such as acetone or diacetone alcohol, ethers such as tetrahydrofuran and dioxane, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, alkylene glycols comprising an alkylene group having 2 to 6 carbon atoms, glycerol, lower alkyl ethers of polyhydric alcohols, lower dialkyl ethers of polyhydric alcohols, sulfolane, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone.
U.S. Pat. No. 5,017,223 (Kobayashi et al.) is directed to a recording material including at least a liquid dispersion medium and an electrolyte contained therein, the electrolyte providing substantially no halogen ion in the liquid dispersion medium under electrolytic dissociation and the recording material being capable of changing its adhesiveness when imparted with a voltage by means of a pair of electrodes, thereby to adhere selectively to either one of the pair of electrodes. The liquid dispersion medium preferably comprises a polyhydric alcohol or polyol solvent. Also suitable are water, triethanolamine, formamide, dimethylformamide, dimethylsulfoxide, N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, N-methylacetamide, ethylene carbonate, acetamide, succinonitrile, dimethylsulfoxide, sulfolane, furfuryl alcohol, N,N-dimethylformamide, 2-ethoxyethanol, hexamethylphosphoric amide, 2-nitropropane, nitroethane, gamma-butyrolactone, propylene carbonate, and the like. These compounds may be used singly or as a mixture of two or more species.
U.S. Pat. No. 4,836,851 (Pawlowski et al.) discloses a dye used in ink compositions for ink jet printing which comprises an aromatic dye molecule having attached to the backbone thereof from one to four polyhydroxyl-substituted groups of specific formulae. The dyes have improved water solubility and improved interaction with paper. The dyes are useful in ink compositions comprising the dye, water, and a water miscible organic solvent. Examples of organic solvents include diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, monomethyl ether, 1,2-dimethoxypropane, an alcohol such as methanol, sulfolane, formamide, N-methyl-2-pyrrolidone, propylene carbonate, oxidipropionitrile, or mixtures thereof.
U.S. Pat. No. 4,790,880 (Miller) discloses an ink suitable for use in ink jet printers including (a) a vehicle comprising at least one member selected from the group consisting of water and a water soluble nonaqueous component, and (b) an anionic dye having cations associated therewith. The ink further includes a macrocyclic polyether associated with the cations, the macrocyclic polyether having binding sites and a cavity size suitable for complexing the cations. The ink composition evicences reduced crusting, increased fade resistance, and reduced kogation. The ink vehicle can include water and/or one or more glycols, and may also comprise water and one or more other water soluble nonaqueous components. Examples of other water soluble nonaqueous components include short chain alcohols such as isopropanol, alkanol amines, such as mono, di, and triethanolamine, amides, such as formamide and dimethyl formamide, sulfoxides such as dimethylsulfoxide, sulfones such as sulfolane, and heterocyclic amines such as N-methyl-2-pyrrolidone and 1,3-dimethylimidazolidinone.
U.S. Pat. No. 4,627,875 (Kobayashi et al.) discloses a recording liquid which comprises C.I. Acid Red 8 as a recording agent for forming an image and a liquid medium comprising at least (a) a member selected from the group consisting of polyethylene glycol, polyethylene glycol monomethyl ether, and a mixture thereof, (b) a member selected from the group consisting of diethylene glycol, sulfolane, and a mixture thereof, (c) a member selected from the group consisting of N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and a mixture thereof, and (d) water.
U.S. Pat. No. 4,585,484 (Haruta et al.) discloses a recording liquid comprising a dye selected from C.I. Direct Blue 199, C.I. Direct Yellow 86, and C.I. Food Black 2 as the recording agent for forming an image and a liquid medium for dissolving or dispersing the recording agent therein, the liquid medium comprising at least (a) either one or both of polyethylene glycol and polyethylene glycol monomethyl ether, (b) either one or both of diethylene glycol and sulfolane, (c) either one or both of N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone, and (d) water.
U.S. Pat. No. 4,840,674 (Schwarz) discloses an ink composition which comprises a major amount of water, an organic solvent selected from the group consisting of tetramethylene sulfone, 1,1,3,3-tetramethyl urea, 3-methyl sulfolane, and 1,3-dimethyl-2-imidazolidone, which solvent has permanently dissolved therein spirit soluble dyes.
U.S. Pat. No. 5,108,503 (Hindagolla et al.) discloses inks for ink jet printing having improved water resistance and smear resistance when they contain from about 2.5 to 25 percent by weight, preferably from about 7.5 to about 12.5 percent by weight, of 2-pyrrolidone, N-(2-hydroxyethyl)-2-pyrrolidone, or mixtures thereof.
Copending application U.S. Ser. No. 07/738,024, entitled "Ink Jet Compositions and Processes", with the named inventor William M. Schwarz, filed Jul. 30, 1991, the disclosure of which is totally incorporated herein by reference, discloses a thermal ink jet printing process which comprises incorporating into a thermal ink jet printing apparatus an ink composition comprising a colorant and a liquid vehicle which comprises a mixture of water and an organic component selected from the group consisting of: (1) cyclic amides of the formula ##STR1## wherein n is a number from 2 to about 12; R is hydrogen, alkyl or substituted alkyl with from 1 to about 6 carbon atoms, a polyethoxy group of the formula EQU (--CH.sub.2 --CH.sub.2 --O).sub.m --CH.sub.2 --CH.sub.2 --OH
with m being a number of from 0 to about 9, or a polyimine group of the formula EQU (--CH.sub.2 --CH.sub.2 --NH).sub.k --CH.sub.2 --CH.sub.2 --NH.sub.2
with k being a number of from 0 to about 9; R' represents one or more substituents that can replace hydrogen in any of the hydrocarbon portions of the molecule, and is an alkyl group, a halogen atom, a sulfate group, a nitro group, a sulfone group, an amide group, or an acetyl group, wherein x is a number of from 0 to 2n+2; (2) a cyclic amide of the formula ##STR2## wherein n is a number of from 1 to about 12, R is a cyclohexyl group or a butyl group, and R' represents one or more substituents that can replace hydrogen in any of the hydrocarbon portions of the molecule, and is an alkyl group, a halogen atom, a sulfate group, a nitro group, a sulfone group, an amide group, or an acetyl group, wherein x is a number of from 0 to 2n+2; (3) cyclic esters of the formula ##STR3## wherein n is a number of from 1 to about 12, R represents one or more substituents that can replace hydrogen in any of the hydrocarbon portions of the molecule, and is an alkyl group, a halogen atom, a sulfate group, a nitro group, a sulfone group, an amide group, or an acetyl group, wherein x is a number of from 0 to 2n+2; (4) amides of the formula ##STR4## wherein R and R' are hydrogen atoms, alkyl groups, or substituted alkyl groups with from 2 to about 20 carbon atoms, polyethoxy groups of the formula EQU (--CH.sub.2 --CH.sub.2 --O).sub.m --CH.sub.2 --CH.sub.2 --OH
with m being a number of from 0 to about 9, or polyimine groups of the formula EQU (--CH.sub.2 --CH.sub.2 --NH).sub.k --CH.sub.2 --CH.sub.2 --NH.sub.2
with k being a number of from 0 to about 9, wherein R and R' can be bonded to each other to form a ring, and wherein R" is hydrogen or alkyl, with alkyl preferably having from 1 to about 20 carbon atoms; and mixtures thereof; and heating selected nozzles in the printing apparatus containing the ink, thereby causing droplets of the ink to be ejected in an imagewise pattern onto a substrate.
Although known ink compositions and ink jet printing processes are suitable for their intended purposes, a need remains for ink compositions with enhanced waterfastness. In addition, there is a need for waterfast inks with lowered viscosity. Further, a need exists for waterfast inks which generate images exhibiting enhanced edge sharpness. Additionally, there is a need for waterfast inks with enhanced drying rates. There is also a need for ink compositions which exhibit high frequency response in ink jet printing systems. A need also exists for ink compositions exhibiting both relatively low viscosity and relatively high surface tension. In addition, there is a need for ink compositions which do not exhibit rapid drying or clogging within the nozzles of an ink jet printer. Further, there is a need for ink compositions which exhibit good shelf stability. Additionally, there is a need for ink compositions wherein the ink components do not react with each other to any significant degree over time.